The present invention is related to control systems for the rotary positioning of a remote antenna from a control apparatus positioned conveniently relative to an operator and is described with particular reference thereto, however the remote positioning of any type of device is contemplated within the precepts of the present invention.
Antenna rotators presently enjoy considerable acceptance among operators of citizen band base stations and ham-amateur radios. To some extent, TV viewers and TM radio listeners in fringe reception areas also find the use of rotators beneficial. These rotator systems standardly include a motor arrangement mounted remotely on a tower, roof or other raised support with the antenna, in turn, mounted to the motor for rotation therewith relative to the support. Conveniently located near the TV or radio equipment is a control console which generally includes a manually actuated switch for controlling positioning of the antenna through operation of the remote motor.
It is desirable that an operator know of the position of the remote antenna and for this reason the control console generally includes an indicator which may take the form of a rotary dial. This rotary dial is moved to a position corresponding to the desired position of the antenna, and the system functions to bring the antenna into alignment with the indicator. Generally, the antenna motor is capable of rotating through only one complete revolution as a result of structural limitations such as electrical connections. The two extremes of the 360.degree. of travel are customarily indicated at the control console by limit switches at the antenna. Connection of the console to the remote antenna is accomplished by a multiconductor cable.
Control of the antenna position has most often been accomplished through use of electrical circuitry involving bridges and DC-balance. When the indicator and antenna are correspondingly positioned, the bridge is in balance. Various methods may be used to turn off control of the antenna motor once balance is reached, or more precisely, as close to balance as possible. Generally, the antenna has passed the balance position before power can be disconnected, and reverse operation is required to obtain true balance. Reverse operation of the antenna motor agains results in the balancing position being overrun, although to a smaller degree than the initial operation. Subsequent reversing operations of the motor result in increasingly smaller overruns until, eventually, balance is attained. Commercially accepted units have approximated balance in the above scheme by disconnecting the antenna motor power at one of the earlier "balance" indications and accepting the relatively small overrun error corresponding therewith.